Process and device for the reduction of energy consumption in the operation of spinning elements

ABSTRACT

The present invention provides a process and device for the reduction of energy consumption in operating spinning elements in driving spinning rotors of open-spinning machines or the spindle drive of ring spinning machine or the roving frame. It is the object of the invention to constantly keep energy consumption in the operation of spinning element at a minimum. Contact pressure between each spinning element and the indirect driving device is adjusted as a function of the momentary difference between the rotational speed of the spinning element and of its driving device in stationary operation while rotational speeds only nominally change, so that the slippage between indirect driving device and spinning element remains constant in time.

BACKGROUND OF THE INVENTION

The instant invention relates to a process and device for reducingenergy consumption in the operation of spinning rotors of an open-endspinning machine or in the operation of the spindles of ring spinningmachines or of the roving frame.

The spinning elements are considered, for example, to be spinning rotorsand spindles. The drive of the spinning elements is designed so thatindirect driving means (belts or drive disks) are pressed interlockinglyagainst the driving surface assigned to the spinning element. This drivecan also be designed so that a motor drives a group of spinning elementsby means of a belt drive, or so that an indirect motorized individualdrive is provided for each spinning element, whereby belts or drivingdisks are acting as indirect driving means.

It is known that a consumption of energy is expended as a result of theslip between spinning elements and their indirect driving means, andthat this slip is not negligible from the point of view of energyconsumption even when optimal production conditions are ensured. Theadmissible deviation in rotational speed for the nominal operation ofthe rotors lies within a tolerance range of approximately ±2% withoutaffecting the product quality. The deviations of rotational speeds ofthe rotors from each other lie within a tolerance range of ±1.5%. Fromthis, it appears clearly that due to the tolerance of the rotationalspeeds of rotors from each other the electric consumption is notminimal, especially when rotors are driven by group drives by means ofbelts and a drive motor. This situation increases the overallconsumption of energy by the spinning machine since the duration ofnormal operation is very long as compared with run-up and stoppage.

DE-OS 39 42 402 describes a tangential belt drive of an open-endspinning machine in which the spinning rotors of several adjoiningspinning units are driven. The described actuating mechanism is directedonly upon the alternation between rotor, brake and pressure roller. Thismakes it possible to increase the contact pressure by an always constantvalue during the run-up of the spinning machine and to reduce it againas normal operation starts. This process is conditioned upon the actionof a service carriage upon the common actuating mechanism of brake andpressure roller. The run-up phase takes place in a matter of seconds, sothat the energy savings which can be obtained are minimal. Since theintervention of the automatic service carriage is necessary, the effectof energy savings applies in each instance only to one single rotor ofthe spinning machine, whereas the machine has, as a general rule, over200 rotors. The actual economic result with respect to energy savingsfor the entire machine is very low. The total time for all piecingprocesses in a spinning machine per shift is considerably lower than thetotal time of yarn production per shift. It is therefore a disadvantagethat no energy saving can be achieved with this solution for the entiretime of yarn production of the spinning machine. For this criticalperiod of time, the solution is absolutely unsuitable in achieving anykind of energy saving.

DE-OS 34 13 764 describes a device having similar disadvantages. Theknowledge of these two solution is obviously insufficient to achieveenergy savings with economic impact for the entire operating time of themachine per shift.

As stated in the article "Autocoro 240 for the production of fine rotoryarns", Chemiefasern/Textilindustrie, 41./93, January 1991, page 41,efforts to reduce energy consumption in a spinning machine have tendedtowards the utilization of rotors with smaller rotor diameters forinstance, the control of drives with frequency reversers or theutilization of new twin disk bearings for the rotors. In the describedsolutions no possibilities are shown on how the conventional pressureroller may be used to contribute to a reduction of electricalconsumption to a minimum during the entire time of production.

The solution according to DE-AS 15 10 840 achieved an improvement overthe rigid pressure which is independent of rotational speed. It is,however, a disadvantage of this solution that the force of contactpressure is changed only centrally, i.e. simultaneously and uniformly atall pressure rollers. The existing tolerance (±1.5%) for the rotationalspeed difference between spinning elements for example, cannot be takeninto consideration in any satisfactory manner for the reduction ofenergy consumption. It is furthermore disadvantageous for the contactpressure to be controlled only centrally, i.e. the reactions toadjustments cannot be recognized, and this results in energy loss forthe individual spinning element because of the tolerance. Until now theexisting tolerance has prevented any further lowering of energyconsumption during spinning operation.

It is a known fact that due to the slippage between spinning elementsand their indirect driving means energy consumption which is notminimal, even when optimal production conditions are ensured, continuesto exist.

It would be possible to achieve considerable savings in three-shiftoperation of a spinning machine in the order of up to one fourth ofpresent energy consumption for the rotor drive, if energy losses due touncontrolled slip between rotor and indirect driving means can beavoided. The existing situation is especially aggravating because thetime for normal operation is very long by comparison with operatingstates such as run-up or stoppage, and therefore exerts the decisiveinfluence upon the potential energy savings.

OBJECTS AND SUMMARY OF THE INVENTION

It is a principal object of the instant invention to provide a processand device for constant keeping energy consumption to a minimum duringoperation of spinning elements.

Additional objects and advantages of the invention will be set forth inpart in the description which follows, and in part will be obvious fromthe description or may be learned by practice of the invention.

The objects are attained with the present invention in that the contactpressure between spinning element and indirect driving means iscontrolled as a function of the momentary speed difference between theindirect driving means and spinning element in stationary operation whenrotational speed is only nominally changed, i.e. the slip betweenspinning element and indirect driving means remains constant duringoperation or during required changes in rotational speed (e.g. duringpiecing). The constant pressure is individually controlled over time foreach spinning element and is thus optimized.

According to the invention, the rotational speeds of the indirectdriving means and that of the applicable spinning element are detectedfor each individual spinning element during operation or during changein rotational speed, are processed into a rotational speed differenceand are transmitted to an individual control of the spinning element inorder to control the contact pressure of the pressure means.

The optimal value of the difference in rotational speeds betweenindirect driving means and spinning element is used as a guide magnitudefor the control circuit. This optimal value of the difference inrotational speeds is found empirically for each individual spinningelement and is established as a set point. The actual value of thedifference between the rotational speed of the driving means and thespinning element is constantly detected and is constantly compared withthe given optimal value of the rotational-speed difference betweendriving means and spinning element.

When the difference in rotational speed deviates from the optimal value,the contact pressure of the pressure means as defined in relation to theindirect driving means or the spinning element is adjusted as a functionof the control intensity via an amplifier. The result is a constantcontact pressure which is adjusted for constant slip. This process isconstant during the entire operation of the spinning element.

A further advantage to be achieved with this invention consists inparticular in the fact that energy savings of up to 25% over the presentconventional consumption of a spinning element drive can be proven inthe operation of the spinning machine as an economically measurableadvantage.

Furthermore, no changes in the process are required when going fromnormal operation to piecing operation, since minimum energy consumptionin operation is achieved in each different mode of operation. Most ofthe energy savings result however from the normal spinning operationitself.

A further advantage consists in the fact that the function of theinvention is independent of the slip differences occurring from spinningelement to spinning element due to manufacturing tolerances andfrictional values or to such influences as network voltage fluctuations.

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the invention, notlimitations of the invention and, together with the description, serveto explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an example of the prior art solution, according to the stateof the art and shows static pressing of the rotor shaft against thedriving disk,

FIG. 2 shows a modular mimic display of the control of the contactpressure between rotor shaft and drive disk according to the presentinvention; and

FIG. 3 shows an electro-mechanical adjusting element of the pressureroller in a group drive in which the rotors are driven by means oftangential belts.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the presently preferredembodiments of the invention, one or more examples of which areillustrated in the drawings. Each example is provided by way ofexplanation of the invention, not limitation of the invention. Thenumbering of components in the drawings is consistent throughout theapplication, with the same components having the same number in each ofthe drawings.

FIG. 1 shows an indirect individual drive of the rotor according to thestate of the art. A known twin disk bearing is used here. As is known,the drive by electric motor is made up of the elements of invertedrectifier 1 and electric motor 2. The driving disk 3 is rigidlyconnected to the motor shaft. In the nip formed by driving disk 3 and apair of supporting disks 5, the rotor shaft 4 and the rotor is supportedand in contact. The supporting disks 5 are provided with a springpressure 6. This spring pressure 6 according to FIG. 1 is exertedpermanently with a constant spring force, so that the rotor shaft 4 ispressed permanently and with constant force against the drive disk 3.The rotational-speed sensor 8 records the momentary rotational speed ofthe drive disk 3 and supplies its rotational-speed values to adesired-value/actual-value SW comparator, i.e. the actual value of therotational speed is compared with a desired rotational speed. Thecontroller 7 functions on basis of the found control difference. Thecontroller 7 is connected to the inverted rectifier 1. The rotationalspeed of the motor 2 is changed by the inverted rectifier 1 as afunction of the magnitude of the control difference. The shown controlcircuit thus serves to control the rotational speed of the drive. Thespring pressure 6 is static and is not connected to the control circuit.

According to the present invention, indirect individual drive of a rotorusing a twin disk bearing is the starting point in FIG. 2. A secondcontrol circuit is introduced in addition to the existing controlcircuit. The magnitude of adjustment in the second circuit is adifference in rotational speed. For this purpose the rotational-speedsensors 8 and 9 are connected via a difference former D and a setpoint--actual value comparator SWD to a regulator 10. According to theprocess an empirically determined optimal value of the difference inrotational speed between the speed of the driving disk 3 and the rotorshaft 4 is given as the set point of rotational speed difference SWD.Each of the rotational-speed sensors 8 and 9 permanently signals thepresent rotational speed of driving disk 3 and rotor shaft 4. Thedifference former D forms the difference between the rotational speed ofthe driving disk 3 and that of the rotor shaft 4. This difference valueis an actual value which is compared with the set point of therotational speed difference SWD. In case of positive or negativedeviation (regulating difference) from the rotational speed differenceSWD the amplifier 11 is actuated via regulator 10 in such manner thatthe contact pressure is increased or reduced accordingly via actuator12. This permanent adjustment also ensures optimal operationdynamically. The actuator can be, for example, a hydraulic or pneumaticvalve with working piston, serving as the contact pressure means, or anelectric lifting magnet, whereby this assembly exerts the definedcontact pressure upon the rotor shaft 4 via supporting disks 5 so thatsaid rotor shaft 4 is constantly pressed against the driving disk 3 witha defined force.

It is also possible to build an embodiment (FIG. 3) which drives severaladjoining spinning elements simultaneously by means of a tangential belt13 for an open-end spinning machine. In FIG. 3, the rotor drive of spinbox A and spin box B is shown schematically and selectively. Theconnection to the respective control circuits is not shown. Theindividual pressure rollers 14 are assigned individual actuators whichconsist of magnet coil 17 and movable iron core 16. The pressure roller14 is normally supported rotatably on one end of a swivelling lever 15.In the facing arm of the lever a rod with an iron core 16 is installedvia an appropriate articulation mechanism. The iron core is supportedinside the magnet coil 17. If the contact pressure is to be increased,the iron core 16 is pulled into the interior of the coil with a definedforce so that the pressure roller 14 presses upon tangential belt 13with a precisely defined force on basis of known lever ratios. If thiscontact pressure is to be reduced in a controlled manner, a change inthe magnetic field caused by the controlling means causes the iron coreto be pushed out of the interior of the coil in a defined manner.According to the process of the invention, actual values of thetangential-belt speed and of the rotational speed of the motor aredetected and are processed into a difference in rotational speeds sothat each spinning station can be controlled individually by its owncontrol circuit (as described according to FIG. 2) so that a minimumenergy consumption can be attained at all times. The advantage consistsfurthermore in a reduction of mechanical outlay required for control ofa plurality of spinning rotors.

I claim:
 1. A process for controlling driving of textile machinespinning elements during all operations in which they are driven throughdirect contact with a driven device, said process reducing the energyconsumption required for operation of the spinning elements, saidprocess comprising the steps of:determining the actual rotational speeddifference between a spinning element and the driven device; and varyingthe contact pressure between the spinning element and driven device as afunction of the actual difference of the rotational speeds thereof. 2.The process as in claim 1, further comprising empirically determining anoptimum set point rotational speed difference between the spinningelement and driven device and comparing the actual rotational speeddifference to the optimum set point rotational speed difference, andcontrolling the contact pressure as a function of the deviation betweenthe actual difference and the optimum set point difference.
 3. Theprocess as in claim 2, further comprising determining the deviationbetween the actual rotational speed difference and optimum set pointrotational speed difference with a control circuit which adjusts thecontact pressure between the driven device and spinning element as afunction of the determined deviation.
 4. The process as in claim 2,wherein the contact pressure is increased if the deviation betweenactual rotational speed difference and optimum set point rotationalspeed difference is positive.
 5. The process as in claim 2, wherein thecontact pressure is decreased if the deviation between actual rotationalspeed difference and optimum set point rotational speed difference isnegative.
 6. The process as in claim 2, wherein the textile machineincludes a plurality of spinning elements and wherein said processcontrols the contact pressure between each individual spinning elementof the textile machine and individual driven devices associated witheach individual spinning element.
 7. The process as in claim 2, whereinthe textile machine includes a plurality of spinning elements andwherein said process controls the contact pressure between eachindividual spinning element of the textile machine and a common drivendevice.
 8. A textile machine having a spinning element driving controldevice for controlling contact pressure between a spinning element andan associated driven device through essentially all phases of operationof said spinning element, said device significantly reducing the energyconsumption required for operation of the spinning element, saidspinning element driving control device further comprising:a contactpressure adjusting device, said adjusting device operably configured tomaintain the contact pressure between said spinning element and saiddriven device; and control means operably configured with said adjustingdevice for varying the contact pressure between said spinning elementand said associated driven device as a function of the actual rotationalspeed difference between the spinning element and the driven device. 9.The machine as in claim 8, wherein said control means comprises acomparator device for determining the deviation between the actualrotational speed difference of the spinning element and the drivendevice and a predetermined optimum set point rotational speed differencebetween the spinning element and the driven device.
 10. The machine asin claim 9, further comprising an actuator device in communication withsaid comparator device and configured to adjust the contact pressurebetween said spinning element and said driven device as a function ofsaid deviation between said actual rotational speed difference and saidoptimum set point rotational speed difference.
 11. The machine as inclaim 8, further comprising a speed sensor disposed so as to measure therotational speed of said spinning element, and a speed sensor disposedso as to measure the rotational speed of said driven device, and adifferencing circuit operatively configured with said sensors fordetermining said actual rotational speed difference between saidspinning element and said driven device.
 12. The machine as in claim 8,wherein said device is configured with a plurality of spinning elementswherein each spinning element has an associated individual drivendevice, said adjusting device configured to adjust the contact pressurebetween each spinning element and its associated individual drivendevice.
 13. The machine as in claim 12, wherein said individual drivendevice includes a twin disk bearing, said adjusting device operablyconnected to said twin disk bearing so that said adjusting device actsupon said twin disk bearing in order to adjust the contact pressure. 14.The machine as in claim 13, wherein said adjusting device includes avalve with a movable piston, said piston acting against said twin diskbearing.
 15. The machine as in claim 14, wherein said common drivendevice includes a tangential driving belt, said adjusting device actingupon said tangential driving belt.
 16. The machine as in claim 15,wherein said adjusting device includes a mechanism for adjusting thepressure of a pressure roller relative said tangential belt.
 17. Themachine as in claim 16, wherein said mechanism includes an magneticlifting device operably configured with said pressure roller fordisplacing said pressure roller relative said tangential belt.
 18. Themachine as in claim 8, wherein said device is configured with aplurality of spinning elements wherein each spinning element is drivenby a common driven device, said adjusting device is configured to adjustthe contact pressure between each spinning element and said commondriven device common to a plurality of said spinning elements.
 19. Atextile machine, said machine comprising:a plurality of spinningelements; a driven device operably configured to contact said spinningelements for rotating said spinning elements; adjusting means foradjusting the contact pressure between said spinning elements and saiddriven device; control means operably configured with said adjustingdevice for varying the contact pressure between said spinning elementsand said associated driven device as a function of the actual rotationalspeed difference between the spinning elements and the driven device.20. The textile machine as in claim 19, wherein said control meanscomprises a comparator device for determining the deviation between theactual rotational speed difference of the spinning element and thedriven device and a predetermined optimum set point rotational speeddifference between the spinning element and the driven device.